Sure, Bill Murray's wife would be first hand testimony - Presumably she would need to have some corroborating evidence otherwise it's just he said/she said.
Incorrect. Learn moar law.
https://www.slgattorneysflorida.com/the-state-only-has-one-witness-isn-t-that-hearsay.html"We often get questions about whether the State can convict you of a crime when they only have one single witness in a "he said/she said" type of case. We usually get the question, "Isn't that hearsay?" Is "he said/she said" testimony hearsay and inadmissible?
No. Eyewitness testimony is not hearsay. Hearsay relates to when a witness testifies about an out of court statement. For example, if Jill testifies, "John told me that Phil punched him," this statement is hearsay because Jill is testifying about John's out of court statement. Now if John testifies that Phil punched him, that is not hearsay, because John is testifying to what happened, not what somebody told him.
Also, hearsay is not always inadmissible. There are many exceptions to the hearsay rule where an out of court statement would be admissible."
https://splinternews.com/people-are-convicted-based-on-one-witness-all-the-time-1829367479People Are Convicted Based on One Witness All The Time"I rob you on a dark, deserted street at night. You call the police. You describe me. The police find me. You confirm it was me. You testify against me. I go to jail. This sort of thing is completely normal.
Sure, the police and prosecutors would like to have as much evidence as possible. They would like to have another witness, or my DNA, or to find the items that I stole from you in my possession. But if they don’t have any of those additional things—if they only have your own testimony that I robbed you—I have news for you: they will still arrest me. And, if the jury finds your testimony to be credible, they will find me guilty, and I will go to jail."